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Friday, January 10, 2014

For total output power of cell phone jammer

For total output power of cell phone jammer is about 0.5W
The definition of the object of study (as a body of two titles, the fourth Times New Roman, bold, left empty word, the same below). China PTAC is the countrys largest mobile phone distributors, sales of mobile phones more than 40 million per year, accounting for almost half of the country. × × Logistics Co., Ltd. is the countrys largest mobile phone carrier, specializing in China PTACs mobile phone distribution business, and its mode of operation on behalf of the logistics of Chinas mobile phone model. (Times New Roman, line spacing, 20 lbs). Characteristics (of the people on the phone the logistics needs of the three title as the text, using the small 4 Times New Roman, bold, left empty word, the same below). It is according to the corresponding standard and specification of cell phone jammer .
The rise of mobile logistics for manufacturers and agents to provide quality transportation platform. Can send and receive MMS from "Big Brother" had only limited to the basic call functions, and today, listen to MP3 music, wireless Internet and even can be used for camera phone, regardless of the function how to increase, what changes shape, it is a mobile phone, you need to logistics service providers connected to the identity of third manufacturers and consumers by the manufacturer or distributor does not appear to bear all of the roles of sales logistics, third-party logistics service providers can play a role irreplaceable. However, the development of the logistics industry, logistics service providers as soon as possible to achieve the integration of logistics resources.According to the nature of the work divided into several departments, organizational structure and reasonable. Each department are relatively independent, but related to each other, very close link between the lack of a part of the whole work is completed. So the flow of information between departments maintain the top priority.
Nokia is a mobile communications products to multinational corporations, headquartered in Finland, the global workforce of about 58,800 people, is a global leader in mobile communications industry. Nokia is listed in Helsinki, Finland, United Kingdom, London, Stockholm, Sweden, France, Paris, Frankfurt, Germany and the United States, New York, and shareholders all over the world. Nokias history began in 1865, a wood pulp factory. In 1967, the main production of cardboard Nokia, the Finnish rubber factory mainly produces sets of boots, and Finnish Cable Works jointly for the Nokia Group, the business covers several areas, including paper, chemical, rubber, etc.. Nokias telecommunications sector is the Finnish Cable Works started in the Electronics Division was established in 1960.

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Tuesday, September 10, 2013

Robot Shield for Arduino

The idea behind this post is to bring together some robot designs and transform them in a new device with new hardware and standard software (arduino of course) and so easier to use. These robots have three things in common: a mechanical structure, the hardware and the software. While the mechanical part is necessarily different.

We wanted to understand if there was a hardware board that could be common, with a unique development system. The choice, quite obviously, has the Arduino board, which with its development environment is perfect to create similar projects.

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Thursday, August 8, 2013

Simple Automatic Switch For Audio Power Amplifier

Circuit of an automatic switch for audio power amplifier stage is presented here. The circuit uses stereo preamplifier output to detect the presence of audio to switch the audio power amplifier on only when audio is present. The circuit thus helps curtail power wastage. IC1 is used as an inverting adder. The input signals from left and right channels are combined to form a common signal for IC2, which is used as an open loop comparator. IC3 (NE556) is a dual timer. Its second section, i.e., IC3(b), is configured as monostable multivibrator. Output of IC3(b) is used to switch the power amplifier on or off through a Darlington pair formed by transistors T1 and T2. IC3(a) is used to trigger the monostable multivibrator whenever an input signal is sensed.

Circuit diagram:

Automatic Switch For Audio Power Amplifier Circuit Diagram

Under ‘no signal’ condition, pin 3 of IC2 is negative with respect to its pin 2. Hence the output of IC2 is low and as a result output of IC3(a) is high. Since there is no trigger at pin 8 of IC3(b), the output of IC3(b) will be low and the amplifier will be off. When an input singal is applied to IC1, IC2 converts the inverted sum of the input signals into a rectangular waveform by comparing it with a constant voltage which can be controlled by varying potentiometer VR1. When the output of IC2 is high, output pin 5 of IC3 goes low, thus triggering the monostable multivibrator. As soon as the audio input to IC1 stops, pin 5 of IC3 goes high and pin 1 of IC3 discharges through capacitor C3, thus resetting the monostable multivibrator.

Hence, as long as input signals are applied, the amplifier remains ‘on.’ When the input signals are removed, i.e., when signal level is zero, the amplifier switches off after the mono flip-flop delay period determined by the values of resistor R8 and capacitor C3. If no input signals are sensed within this time, the amplifier turns off—else it remains on. Power supply for the circuit can be obtained from the power supply of the amplifier. Hence, the circuit can be permanently fitted in the amplifier box itself. The main switch of the amplifier should be always kept on. Resistors R1 and R2 are used to divide single voltage supply into two equal parts.

Capacitors C1 and C2 are used as regulators and also as an AC bypass for input signals. Diode D1 is used so that loading fluctuations in power amplifier do not affect circuit regulation. Transisitor T2 acts as a high voltage switch which may be replaced by any other high voltage switching transistor satisfying amplifier current requirements. Value of resistor R10 should be modified for large current requirement. The LED glows when the amplifier is on. The circuit is very useful and relieves one from putting the amplifier on and off every time one plays a cassette or radio etc.

http://streampowers.blogspot.com/2012/06/simple-automatic-switch-for-audio-power_11.html

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Wednesday, August 7, 2013

Soft Start For Switching Power Supply

Switching power supply whose output voltage is appreciably lower than its input voltage has an interesting property: the current drawn by it is smaller than its output current. However, the input power (UI) is, of course, greater than the output power. There is another aspect that needs to be watched: when the input voltage at switch-on is too low, the regulator will tend to draw the full current. When the supply cannot cope with this, it fails or the fuse blows. It is, therefore, advisable to disable the regulator at switch-on (via the on/off input). until the relevant capacitor has been charged. When the regulator then starts to draw current, the charging current has already dropped to a level which does not overload the voltage source.

Circuit diagram:
Soft Start Circuit Diagram For Switching Power Supply

Soft Start Circuit Diagram For Switching Power Supply

Soft Start Circuit For Switching Power Supply

The circuit in the diagram provides an output voltage of 5 V and is supplied by a 24 V source. The regulator need not be disabled until the capacitor is fully charged: when the potential across the capacitor has reached a level of half or more of the input voltage, all is well. This is why the zener diode in the diagram is rated at 15 V. Many regulators produced by National Semiconductor have an integral on/off switch, and this is used in the present circuit. The input is intended for TTL signals, and usually consists of a transistor whose base is accessible externally. This means that a higher switching voltage may be applied via a series resistor: the value of this in the present circuit is 22 kΩ. When the voltage across the capacitor reaches a level of about 17 V, transistor T1 comes on, whereupon the regulator is enabled.

Source: National Semiconductors

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Monday, May 13, 2013

Flashing LEDs for the music

This circuit was purposely designed as a funny Halloween gadget. It should be placed to the rear of a badge or pin bearing a typical Halloween character image, e.g. a pumpkin, skull, black cat, witch, ghost etc. Two LEDs are fixed in place of the eyes of the character and will shine more or less brightly following the rhythm of the music or speech picked-up from surroundings by a small microphone. Two transistors provide the necessary amplification and drive the LEDs.

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Friday, May 3, 2013

Oil Temperature Gauge for 125 cc Scooter

Lots of Far-Eastern scooters are fitted with GY6 engines. These already elderly units are sturdy and economical, but if you want to “push” the power a bit (so called ‘Racing’ kits, better handling of the advance, etc.), you soon find yourself faced with the problem of the engine temperature, and it becomes essential to f it a heat sink (of ten wrongly referred to as a ‘radiator’) on the oil circuit. Even so, in these circumstances, it’s more than reassuring for the user to have a constant clear indication of the oil temperature. Here are the specifications we set for the temperature gauge we wanted to build:

Oil Temperature Gauge Circuit Diagram :
Oil Temperature Gauge-Circuit Diagram

no moving parts (so not meter movement), as scooters vibrate a lot!;
as cheap as possible (around £12);
robust measuring transducer (avoid NTC thermistors and other ‘exotic’ sensors);
temperature range 50–140 °C. (122 – 291 °F);
audible and visual warning in case of dangerous temperature;
compact;
waterproof.

Let’s start by the sensor. This is a type-K thermocouple, as regularly used by multimeter manufacturers. Readily available and fairly cheap, these are robust and have excellent linearity over the measurement range we’re interested in here. The range extends from 2 mV to 5.7 mV for ten measurement points. The positive output from the thermocouple is applied to the non-inverting input of IC3.A, wired as a non-inverting amplifier. Its gain of 221 is determined by R1 and R2. IC3 is an LM358, chosen for its favourable characteristics when run from a single-rail supply. IC3.B is wired as a follower, just to avoid leaving it powered with its pins floating.

IC3.B output is connected to pin 5 of IC1, an LM3914. This very common IC is an LED display driver. We can choose ‘point’ or ‘bar’ mode operation, according to how pin 9 is connected. Connected as here to the + rail, the display will be in ‘bar’ mode. Pin 8, connected to ground, sets the full scale to 1.25 V. R3 sets the average LED current. Pin 4, via the potential divider R7/R8+R9, sets the offset to 0.35 V. Using R8 and R9 in series like this avoids the need for precision resistors.

As per the LM3914 application sheet , R4-R5-R6 and C5 will make the whole display flash as soon as D10 lights (130 °C = 226 °F). Simultaneously, via R10 and T1, the (active) sounder will warn the user of overheating. Capacitor C6 avoids undesirable variations in the reference voltage in ‘flashing’ mode. IC2 is a conventional 7808 regulator and C1– C4 filter the supply rails. Do not leave these out! D1 protects the circuit against reverse polarity.

The author has designed two PCBs to be fit-ted as a ‘sandwich’ (CAD file downloadable from [1]). In the download you’ll also find a document with a few photos of the project. You’ll note the ultimate weapon in on-board electronics: hot-melt glue. Better than epoxy (undoable!) and quite effective against vibration.

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Wednesday, April 10, 2013

Solid State Switch For Dc Operated Gadgets

This solid state DC switch can be assembled using just three transistors and some passive components. It can be used to switch on one gadget while switching off the second gadget with momentary operation of switch. To reverse the operation, you just have to momentarily depress another switch.

The circuit operates over 6V-15V DC supply voltage. It uses positive feedback from transistor T2 to transistor T1 to keep this transistor pair in latched state (on/ off), while the state of the third transistor stage is the complement of transistor T2’s conduction state.

Initially when switch S3 is closed, both transistors T1 and T2 are off, as no forward bias is available to these, while the base of transistor T3 is effectively grounded via resistors R8 and R6 (shunted by the load of the first gadget). As a result, transistor T3 is forward biased and gadget 2 gets the supply. This is indicated by glowing of LED2.

Circuit diagram :

Solid-State Switch For Dc-Operated Gadgets Circuit Diagram

When switch S1 is momentarily depressed, T1 gets the base drive and it grounds the base of transistor T2 via resistor R4. Hence transistor T2 (pnp) also conducts. The positive voltage available at the collector of transistor T2 is fed back to the base of transistor T1 via resistor R3. Hence a latch is formed and transistor T2 (as also transistor T1) continues to conduct, which activates gadget 1 and LED1 glows.

Conduction of transistor T2 causes its collector to be pulled towards positive rail. Since the collector of T2 is connected to the base of pnp transistor T3, it causes transistor T3 to cut off, switching off the supply to gadget 2) as well as extinguishing LED2. This status is maintained until switch S2 is momentarily pressed. Depression of switch S2 effectively grounds the base of transistor T1, which cuts off and thus virtually opens the base-emitter circuit of transistor T2 and thus cutting it off. This is the same condition as was obtained initially. This condition can be reversed by momentarily pressing switch S1 as explained earlier.

EFY lab note. During testing, it was noticed that for proper operation of the circuit, gadget 1 must draw a current of more than 100 mA (i.e. the resistance of gadget 1 must be less than 220 ohms) to sustain the latched ‘on’ state. But this stipulation is not applicable for gadget 2. A maximum current of 275 mA could be drawn by any gadget.

Author : Praveen Shanker - Copyright : EFY

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Universal Tester for 3 pin Devices

Most 3-terminal active components can be tested statically using just an ohmmeter. But when you have a lot of these devices to test, the procedure soon becomes boring. That’s where the idea came from to combine fast, easy testing for these types of device into a single instrument.

The unit described here enables you to test NPN and PNP bipolar transistors, N-or Pchannel FETs or MOSFETs, UJTs, triacs, and thyristors. Regardless of the type of device, the tests are non-destructive. Universal connectors allow testing of all package types, including SMDs (up to a point). The unit lets you change from one type of device to another in a trice. It avoids using a multi-pole switch, as they’re too expensive and hard to ﬁnd.

Universal Tester for 3-pin Devices Circuit diagram:

Here’s how to build a versatile instrument at a ridiculously low cost. IC1 is a 4066 quad CMOS switch which will let us switch between bipolar transistors and FETs. LEDs D1–D4 tell us about the condition of the test device, when we press the ‘Test’ button. The 4066 can only handle a few milliamps, not enough for the other component types to be tested, hence the reason for using relay RE1. This 12 V relay offers two NO contacts. The ﬁrst applies power to the UJT test circuit, the second applies it to the triac and thyristor test circuit.

Extensive testing has shown that the best way to test UJT transistors is to do so dynamically, with the help of a relaxation oscillator. Net-work R11/C1 sets the oscillator frequency to around 2 Hz. On pin B1 of the UJT we find a nice sawtooth, which is not of much interest to us here. However, pin B2 gives good but very short pulses. IC2, wired as a monostable, lengthens these pulses so they can be clearly seen via LED D5.

The relay’s second pole is going to drive the thyristor’ sortriac’s trigger pin. The value of R18 is a good compromise with respect to the varying trigger currents for this type of device. Resistor R17 is important, as the hold-ing current must be high enough for a triac; 250 mA is a good compromise. LED D6 tells you if the device is in good condition or not; but watch out, the test result must be con-ﬁrmed by brieﬂy cutting the power in order to reset the triac.

On the web page for this article [1] you’ll ﬁnd the author’s CAD ﬁles (PCB layout and front panel) along with some photos of his project. On the prototype, the LEDs and the ‘Test’ button were wired onto the copper side of the PCB. The six female connectors for the devices being tested were salvaged, but there are lots of models available on the market (the pitch is standard). The test cable crocodile clips must be as small as possible for testing SMD devices.

Source : http://www.ecircuitslab.com/2012/05/universal-tester-for-3-pin-devices.html

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Monday, April 8, 2013

Longwire Match For SW Receivers

Most
shortwave receivers for use ‘in the shack’ have a 50-coaxial input
(usually a SO239 socket) which is not directly suitable for the high
impedance of a typical long-wire antenna. The problem is usually
overcome by inserting a balun (balanced to unbalanced) transformer whose
primary purpose is to step down the antenna impedance from ‘high’ to
to 50Ω and not, as would be expected, to effect a change from balanced
to unbalanced (note that a long-wire is an unbalanced antenna).
Unfortunately, such a balun may be difficult to obtain, make yourself,
or both. The circuit shown here is a transistorized (i.e.,
inductor-free) equivalent of the wire balun. The grounded-collector
conﬁguration is used because a relatively high input impedance (the
long-wire antenna) has to be stepped down to 50 Ω (the receiver input
impedance).

Longwire Match For SW Receivers Circuit Diagram

Voltage
amplification is not required here. The two anti-parallel diodes at
the antenna input prevent damage to the circuit as a result of static
discharges or extremely strong signals. Like an active antenna, the
circuit receives its supply voltage (in this case, 9V) via the down-lead
coax cable. Current consumption will be of the order of 20mA. The coax
cable should be earthed at the receiver side. The length of the
antenna wire will depend on local conditions and what you hope to be
able to receive. For most SW broadcast service and amateur radio
listening, a wire of about 3m will be sufficient but bear in mind that
the long-wire antenna is prone to pick up electrical interference.

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Sunday, April 7, 2013

DTMF Decoder Circuit For PC

This is a design circuit for decoder circuit that can be use for DTMF circuit for PC. This is the figure of the circuit;

Our DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Windows program can be placed in the minimize mode and still detect tones while you use your computer to do other things like We are now in the process of adding an DTMF decoder which will interface to the sound card game port.

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Choosing the Right Amplifier for your Auto Sound System

Finding the best amplifier for your auto sound system can be a lot easier if you take the time ahead of time to learn what you need and what will work best with the sound system youve selected for your car, truck, or SUV. It helps to understand what an amplifier does in order to purchase the one that will best suit your needs. An amplifier takes a small sound, adds a little boost of its own, and then turns it into a big sound. The more power your amplifier has, the better quality of sound it will provide. An underpowered amplifier will have a thin, tinny sound that is rather unattractive in an auto sound system, or any other sound system for that matter.

You should also take care to remember that the power rating of an amplifier is the maximum power it is capable of expending not the amount that it will regularly use. The RMS rating of an amplifier is a good indication of its power output. One thing that is important to remember is that you should never buy an amplifier based on the maximum output or RMS rating. This number is more often than not incredibly misleading. If a driving, thumping bass beat is important to you then you should make sure that your amplifier has a bass boost button. This button will or switch will give a little bit of a boost to your bass. Its something I can pass on by many bass lovers cannot live without. Not all amplifiers have this so choose wisely and according to your preferences.

When it comes to amplifiers there are essentially four major classes (there are other classes but they are not all that common so I will not dwell on defining them) that represent the quality of sound you should expect from the system.

1) A. This class has a great output of quality sound but wastes huge amounts of energy in the process of creating that wonderful sound.

2) B. This class is slightly better than A as far as it wastes less energy and slightly worse as it produces a somewhat inferior quality of sound.

3) A/B. This resembles either A or B as far as sound and energy waste goes depending on the volume. Lower volumes will utilize the class A qualities of the amplifier while louder volumes are more in keeping with class B.

4) D. This class is primarily decent for producing a good bass sound and little else. The quality of sound and amount of energy wasted are both only moderate and neither are very impressive.

Of course this is the bare bones run through of the very basic amplifier basics. Another thing to note is that many people simply refer to amplifiers as amps rather than saying the entire word. Its slang but its so common that no one will blink if you do it. In fact you are far more likely to get funny looks for calling it an amplifier. Regardless of the small talk an amplifier isnt the end all be all of an auto sound system. It is only important if you feel it is important and many sound systems work splendidly without an extra amplifier to confuse the process and raise the price.

Whenever you decide to buy a new auto sound system for your car, truck, or SUV there is a moment of exhilaration and excitement as this is often a decision youve mulled over for quite a while rather than a spur of the moment decision. This exhilaration is promptly followed by a moment of complete and utter fear, as most of us have no clue what we really need. Hopefully, this has helped you decide whether or not you will need an amplifier and if you will, perhaps you can make a more educated and informed decision as to the type of amp you need.

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Friday, April 5, 2013

3 Transistor Audio Amplifier Circuit for 80 mW

This circuit is for amplifier 80 mW uses positive feedback to get a little more amplitude to the speaker. This is a simple design for a small amplifier. This has a disadvantage in that as the output moves positive, the drop across the 470 ohm resistor decreases which reduces the base current to the top NPN transistor. Thus the output cannot move all the way to the + supply because there wouldnt be any voltage across the 470 resistor and no base current to the NPN transistor. This is the figure of the circuit.

In this circuit, the 1K load resistor is tied to the speaker so that as the output moves negative, the voltage on the 1K resistor is reduced, which aids in turning off the top NPN transistor. When the output moves positive, the charge on the 470uF capacitor aids in turning on the top NPN transistor. The original circuit in the radio used a 300 ohm resistor where the 2 diodes are shown but I changed the resistor to 2 diodes so the amp would operate on lower voltages with less distortion. The transistors shown 2n3053 and 2n2905 are just parts I used for the other circuit above and could be smaller types. Most any small transistors can be used, but they should be capable of 100mA or more current. A 2N3904 or 2N3906 are probably a little small, but would work at low volume.

The 2 diodes generate a fairly constant bias voltage as the battery drains and reduces crossover distortion. But you should take care to insure the idle current is around 10 to 20 milliamps with no signal and the output transistors do not get hot under load. The circuit should work with a regular 8 ohm speaker, but the output power may be somewhat less. To optimize the operation, select a resistor where the 100K is shown to set the output voltage at 1/2 the supply voltage (4.5 volts). This resistor might be anything from 50K to 700K depending on the gain of the transistor used where the 3904 is shown.

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